The present invention relates to a laser beam delivery system that will split a single beam into a plurality of equally sized and shaped laser beams which will be altered and finally directed at an object to facilitate efficient processing of a desired surface of the object, such as a substrate.
While it is currently known in the prior art to split a single laser beam into a plurality of different beams, many of the systems currently available are very cumbersome to operate and do not efficiently process the laser beam once it is split into a plurality of laser beams. In particular, the currently known prior art systems presently available do not facilitate redirecting of the split laser beams efficiently and quickly at a desired surface of an object to be processed and achieve the desired precision of the laser beam delivery system.
Generally, a laser beam is focused or altered, by the inherent optics of the system, to provide either xe2x80x9cfocal point machiningxe2x80x9d or xe2x80x9cimagingxe2x80x9d of the object to be processed. Focal point machining is conventional and well known in the art and generally comprises supplying a laser beam B from a laser L (see FIG. 1) to repeat positioners or galvanometers where the supplied laser beam B is reflected by the mirror, of the repeat positioner or galvanometer M (only one of which is shown for reasons of clarity), to a focusing lens F which, in turn, focuses the supplied beam at an object to be processed O. The objective of focal point machining is to focus and concentrate all of the energy from the laser beam B so that it converges at a desired spot S on the surface of the object to be processed O. It is to be appreciated that the object to be processed O is spaced from the focusing lens F by a distance which is equal to the focal plane FP of the focusing lens F to facilitate converging all of the supplied light at a desired area or spot S on the surface of the object to be processed O and formation of a desired aperture or feature in the object to be processed O.
Imaging is also conventional and well known in the art but, on the other hand, generally comprises a higher finesse and tighter tolerance processing of a desired aperture or feature in the object to be processed O. As with xe2x80x9cfocal point machiningxe2x80x9d, a laser beam B is supplied from a laser L (see FIG. 2) to a repeat positioner or galvanometer (only one of which is shown for reasons of clarity) where the supplied laser beam B is reflected by the mirror M, of the repeat positioner or galvanometer, to a focusing lens F which, in turn, focuses the supplied beam B at an object to be processed O. The objective of imaging is to image an apertured area of the supplied laser beam on the surface of the object to be processed O. To achieve this, the object to be processed O is spaced from the focusing lens F by a distance which is greater than the focal plane FP of the focusing lens F. Conventional imaging geometric lens equations are utilized to determine and/or calculate the process parameters and to optimize the object to image ratio of the imaging system. As such equations and teaching are well known in the art, a further detail discussion concerning the same is not provided.
Wherefore, it is an object of the present invention to overcome the above mentioned shortcomings and drawbacks associated with the prior art.
Another object of the present invention is to develop a laser beam delivery system that will separate a single laser beam into a plurality of equally sized and shaped laser beams, preferably two, three or more separate laser beams, and each one of these equally sized and shaped laser beams is formed to have a substantially or pseudo flat top profile or customized shape optimized for processing.
A further object of the present invention is to collimate each one of the separate equally sized and shaped laser beams, once split by the laser delivery system, and supply each of the collimated and split laser beams to the object to be processed.
Yet another object of the present invention is to provide an illumination prism, along the optical axis of the laser beam delivery system, to facilitate converging of the three separate laser beams, in an overlapped or a partially overlapped manner, to a first mirror of a repeat positioning system, e.g. a galvanometer, so that the three overlapped beams will only be received within and illuminate the clear aperture of the mirror of the repeat positioning system thereby ensuring that all of the supplied laser beam light is reflected by the repeat positioning system, at the object to be processed, to maximize the efficiency of the laser beam delivery system.
A still further object of the present invention is to provide an adjustment mechanism for facilitating movement of the illumination prism, along the optical axis of the laser beam delivery system, to fine tune the degree of convergence or overlap of the separate collimated beams as well as re-expansion and final separation of the three separate collimated beams as the beams enter the F-Theta lens.
Still another object of the present invention is to provide a laser beam delivery system which allows a plurality of separate laser beams, e.g. two, three or more separate laser beams, to process a desired surface of an object to be processed to improve the efficiency of the laser beam delivery system.
Yet another object of the present invention is to provide a trepanning module which facilitates altering of the supplied laser beams so that each laser beam is controlled to spiral either radially inwardly or radially outward in unison with one another.
As is apparent from the following discussion, the term xe2x80x9coverlapxe2x80x9d as used in this patent application and the appended claims, does not necessarily mean that the laser beams must physically overlap or combine with one anotherxe2x80x94this term is intended to mean merely that all three beams sufficiently converge with or toward one another by a sufficient amount so as to pass through the clear aperture of the mirror of the first repeat positioner.
The term xe2x80x9cobject to be processedxe2x80x9d, as used in this patent application, is intended to cover PC boards, substrates, panels, flex circuits and other computer and electronic components in which small apertures, vias or other holes are to be formed in the object to be processed.